1. Field of the Invention
The invention relates to a developing apparatus, a process cartridge, an electrophotographic image forming apparatus and an end portion regulating member.
2. Description of Related Art
Heretofore, a process cartridge system has been adopted in an electrophotographic image forming apparatus using an electrophotographic image forming process. This process cartridge system refers to a system whereby an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally made into a cartridge, which is made detachable mountable to a main body of an image forming apparatus. According to this process cartridge system, the maintenance of the apparatus can be done by an operator himself without resort to a serviceman. Therefore the operability of the apparatus can be markedly improved. So, this process cartridge system is widely used in electrophotographic image forming apparatuses.
Also, in a developing apparatus used in the electrophotographic image forming apparatus, a stationary magnet is disposed in a hollow cylindrical developing roller. By the magnetic force of the magnet, a developer (hereinafter referred to as the “toner”) is attracted to the surface of the developing roller. The layer thickness of the toner adhering to the surface of the developing roller is regulated by a developing blade. By the developing roller being rotated, the toner is carried to a developing portion for visualizing a latent image.
As a method of preventing this toner from leaking out of a developing chamber, there is known a method of bringing a seal member such as belt into contact with the developing roller within the range outside an image formable area.
Also, there is known a method of disposing a ferromagnetic material as a seal member in non-contact with the developing roller, and holding the toner by the magnetic force thereof.
Also, there is known a construction in which a scraping-off member is disposed downstream of a seal member with respect to the rotating direction of the developing roller and a portion of the scraping-off member is brought into contact with the developing roller. This scraping-off member returns the toner having come out from the aforementioned seal member to the downstream side by the rotation of the developing roller again into a developing area so as not to leak outwardly (U.S. Pat. No. 6,205,304).
However, it has sometimes been the case that the developer leaks out along the rotating direction of the developing roller through interstices formed between the developing blade and the seal members provided on the end portions of the developing roller. When the amount of the developer leaking out through the interstices increases, there has been the possibility of the developer adhering to the electrophotographic photosensitive member.